Actually written little by little over 20 years this sonata was given the title #4 simply because it didn’t fit with the connecting tissue of the first three and represents a joyful departure from their contrapuntal seriousness. The first movement starts with a long, tender prelude which ends with a bang and catapults us headlong into a joyous “gallant style” Rondo. The middle movement is a tender Andante which sets up a rousing Allegro finale.